Wafer Dicing with Laser-Guided Bevel Knife Width Control

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Solution Overview

Problem

Conventional wafer dicing methods using diamond knives cause stress on the wafer, leading to back side chipping, especially in low-k wafers, and the use of bevel knives is restricted by the difficulty in controlling the wafer cut width as dicing lane widths shrink.

Innovation Solution

A method involving a laser beam for initial dicing to form a dicing lane, followed by a bevel knife for secondary and tertiary dicing, with precise control of the bevel knife's height and cut width using feedback from the dicing machine to compensate for thickness differences and achieve accurate cut widths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a diamond dicing knife is used to dice the wafer, then the wafer can be separated into chips, but stress is concentrated on the active surface causing back side chipping

Engineering Contradiction:

Improvewafer dicing capabilityVSAvoidwafer integrity (back side chipping)

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent replaces the conventional diamond mechanical dicing knife with a laser beam for the first dicing operation. This substitution eliminates mechanical contact with the wafer's active surface, thereby preventing stress concentration and back side chipping while still achieving effective wafer separation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The dicing process is divided into multiple stages: first dicing with laser beam, second dicing with bevel knife in inactive area, and third dicing with bevel knife on bottom surface. This segmentation allows each operation to serve a specific purpose, with the laser handling the critical active surface separation and subsequent knife operations handling the inactive area and bottom surface.

Inventive Principle:

Principle #1Segmentation

2Reliability

If a bevel knife is used to dice the wafer, then stress problem is solved, but the dicing lane width must be greater than 180 micrometers

Engineering Contradiction:

Improvestress distributionVSAvoiddicing lane width

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent performs a first dicing operation with a laser beam to create a preliminary dicing lane before using the bevel knife. This preliminary action removes material and creates a groove that guides the subsequent bevel knife, enabling the knife to operate effectively in narrower lanes without requiring the dicing lane width to exceed 180 micrometers.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The laser-diced lane serves as an intermediary structure that facilitates the bevel knife operation. The laser-created groove acts as a guide and preparation for the mechanical knife, allowing the bevel knife to function properly in narrow lanes where it would otherwise be ineffective.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Area of stationary object

If the dicing lane width is reduced for advanced packaging, then packaging density increases, but control of wafer cut width becomes difficult

Engineering Contradiction:

Improvewafer area utilizationVSAvoidwafer cut width control

Core Design Contradiction:

Area of stationary objectVSManufacturing precision

Solution Approach 1:

The patent employs feedback from the dicing machine to measure and control the wafer cut width. The system uses the feedback information to activate a compensation mechanism that adjusts the Z-axis position of the bevel knife, ensuring precise cut width control even as dicing lane widths are reduced for advanced packaging applications.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent implements a dynamic compensation mechanism that adjusts the bevel knife's Z-axis position in real-time based on feedback measurements. This dynamic adjustment allows the system to maintain precise cut width control despite variations in wafer thickness and changes in dicing lane width, enabling accurate dicing in narrow lanes.

Inventive Principle:

Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This method allows for precise control of the wafer cut width, enabling the use of bevel knives in narrower dicing lanes, thereby reducing stress on the wafer and improving dicing efficiency and accuracy.

Implementation Method 1

using a laser beam to perform a first dicing on a wafer to form a dicing lane on the wafer

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS20250140612A1Method for wafer dicing

Publication Date: 2025.05.01 SILICONWARE PRECISION IND CO LTD

AI summary

A wafer dicing method is provided, which includes: using a laser beam to perform a first dicing on a wafer to form a dicing lane on the wafer; using a bevel knife of a dicing machine to perform a second dicing in an inactive area of the wafer, wherein, before the second dicing, the bevel knife is raised to compensate for a thickness difference of the wafer in the inactive area and the dicing lane; and using the bevel knife to perform a third dicing in the dicing lane, wherein, during the third dicing, a wafer cut width of the second dicing is used to activate a Z-axis compensation mechanism of the dicing machine, so that the bevel knife cuts to a predetermined wafer cut width. As such, the applicable dicing lane width range of the bevel knife is increased via the precise control of the wafer cut width.